1. Field of the Invention
The invention relates to submarine enclosures for use in protecting repeater apparatus or the like, particularly in fiber optic submarine cable systems.
2. Description of the Prior Art
Although the technology specifically relating to submarine cables employing fiber optic technology is relatively new, there is a substantial amount of prior art relating to submarine enclosures for housing and protecting repeater apparatus and the like relating to submarine electric signal systems. Examples of this prior art are contained in U.S. Pat. 2,155,650; 2,697,739; 3,168,614; 3,201,508 and 3,456,838.
While the requirement for protection of electrical and electronic components within a submarine cable repeater housing is essentially the same in a fiber optic submarine cable system as in a purely electric submarine cable signal system, the interface requirement for fiber optic cable input and output interfaces are somewhat less severe than for electric cables. This is because the slightest penetration of sea water against metallic conductors can produce failure of the system because of the conductivity and inherent corrosiveness of sea water. Although it is, of course, highly desirable to prevent any intrusion of sea water into the fiber optic cable or interface with the repeater housing, the effects of such intrusion are not as immediate or disastrous as long as the sea water penetration into the repeater housing itself does not occur.
The typical prior art aforementioned either involves very complicated and expensive structures or involves permanently sealed structures, or both. A sealed structure for a repeater housing must be essentially rebuilt if it opened for any reason after its original manufacture. It is possible to construct an expendable repeater with housing, but replacement or repair is still a major operation in the typical prior art arrangement. In order to minimize interface losses, the electronic apparatus employed for a repeater in a submarine fiber optic cable arrangement should be void of optic fiber breaks and connections except at the direct input and output of the electronic apparatus of the repeater wherein an optic-fiber-to-optic-fiber connection is not involved. Moreover, a repeater enclosure for a fiber optic submarine cable system should be non-destructively accessible for maintenance or repair and should be consistent with in-line assembly. None of the prior art systems allow for practical in-line assembly, a term which will be more fully understood as this description proceeds.
The manner in which the present invention deals with the prior art disadvantages to provide a submarine housing for repeater apparatus, or the like, in a submarine fiber optic cable system will be appreciated at this description proceeds.